I was watching a cooking show the other nightGood
Eats with Alton Brownthat demonstrated why we get more nutrients
from cooked vegetables than we do from raw vegetables. While cooking destroys
some vitamins, it leaves plenty behind that are more available to our
digestive system. Raw vegetables have more vitamins, but our teeth and
digestive system can't efficiently digest the plant matter that contains
them. Consider how your teeth and jaws have to work to chew a raw carrot.
How long would your teeth last if they were stressed that way at every
meal? Fruits are softer, but they contain sugars and acids that destroy
tooth enamel.

Digesting raw vegetables creates enough excess gas to
cause lots of discomfort. Fruits cause even more severe gastrointestinal
problems. Grains also must be processed before they serve as the staff
of life. Without pounding, grinding, dissolving and heating, wheat,
corns, rice, most legumes and seeds are virtually indigestible- to humans
at least. Cows, birds, and mice can eat grains right off the stalk along
with the stalk itself. Although humans require vegetation as a source
of nutrients and calories, we did not evolve to eat them raw.

But that doesnt make us carnivores. That tender
steak in the upscale restaurant has been hanging around tenderizing
for many weeks before it melts like butter in your mouth. Most cuts of
meats require marinades, stewing, grinding, or pounding with a mallet
before they can be chewed, but chewing is only part of the problem. Eating
raw meat of any kind is risky for humans. Unlike predators such as lions
or wolves, our digestive systems did not evolve to eat unprocessed meat.
Internal organs, such as livers, brains and intestines are protein rich
and easy to chew, but we still never eat them raw. Im not sure why
we cook internal organs, but if we prefer to not eat raw innards is it
reasonable to assume that we evolved on a such a diet? Try to get a two
year old to eat liver, raw or cooked.

Which is another important point. Humans need protein,
and lots of it to develop our big brains. Most of this brain growth takes
place before age five. Salmonella, E. coli, and other bacteria in raw
meat are deadly to infants and toddlers. By age three, children are weaned,
but they still need a high protein diet. Something happened long before
we were Homo sapiens that enabled toddlers to get enough protein to feed
a growing human brain.

We need animal sources of protein. We need vegetables
for vitamins. We need to eat what our teeth cant chew and what our
stomachs cant digest. There are some exceptions.

We can eat raw sea food without much risk. As long as
the water isnt contaminated, and the fish is fresh, sushi is a healthy
source of protein. It also is easy to chew and easily digestible. However,
our bodies can't manufacture most of the vitamins that are required for
good health, so our teeth and digestive systems didn't evolve solely on
sole. And we are still left with a vitamin deficiency.

That brings us back to what we do eat, and what people
all over the world eat: cooked meat and vegetables. Taphonomy
is a branch of science that studies what foods a species teeth evolved
to eat based on the types of teeth the species has. Cats and dogs have
teeth suitable for ripping flesh. Cows and horses have blunt teeth that
suitable for eating plants. Great apes have teeth that grind vegetation.
Human teeth cannot rip flesh nor sufficiently grind plants to release
nutrients. Our teeth are smaller than other apes but our teeth work very
nicely if vegetables, grains, and meat have been cooked.

Until recently I believed, like most non-anthropologists,
that hominids tamed fire after we evolved our bigger brains. However,
according to The Tree of Origin there was evidence of fire
control 300,000 to 400,000 years ago. Hominids smaller teeth appeared
250,000 years ago. The authors suggested there are strong signals that
cooking originated more than 1.6 million years ago. Another source, The
Demonic Male by Richard Wrangham & Dale Peterson (1996) cites
the same theory.

Australopithecus, lived about 2 million years ago. They
didn't have much of a bigger brain than modern gorillas, but they were
smart enough to use cutting tools to scrape meat from bones. These woodland
apes also had smaller mouth and teeth than chimpanzees do. We will never
know if they used fire to sanitize, tenderize and preserve food. Our modern
teeth and digestive system suggest that they did.

It is possible, and even very likely, that use of fire
to alter food played an important part in our evolution. Unlike other
animals, we are mesmerized by fire rather than terrified of it. Cooking
food removes hazards of bacteria and parasites, allows us to exploit food
sources that we otherwise couldn't use, and even begins the digestive
process for us. Did our hominid ancestors move down from the tree tops
to walk or to cook? The idea at least is something to chew on the next
time you sit around a campfire.